Regional magnetic field modelling: A review.

Abstract

Regional models of the earth's magnetic field have developed considerably since the days of hand contouring. They have incorporated varying levels of mathematical sophistication, from partial "mutual consistency" on a surface to full electromagnetic consistency in three-dimensional space. Each method has its advantages and its limitations. Some of the methods allow for radial variation so that data acquired at different altitudes can be analyzed directly, and so that fields from the resulting models can be calculated at any altitude. For other methods, altitude continuation is theoretically possible but numerically difficult and statistically unreliable. Some methods are limited, for numerical reasons, to small areas or are able to represent only fairly long wavelengths. The different methods also differ greatly with respect to their mathematical and computational complexity, the less complex methods also usually being more subjective.

Bulgarian Geomagnetic Reference Field (BulGRF) for 2015.0 and secular variation prediction model up to 2020

“…We checked if the geometrical constraint (Haines, 1990) is satisfied using the equation (Finlay et al, 2016) and the latest edition of IGRF model (Thébault et al, 2015), which provides a reference field model for the same epoch. In Fig.…”

“…Although the surface polynomials were the first analytical method used to produce regional models (Haines, 1990) In the present research we fit a second degree polynomial of the form (Buchvarov and Kostov, 1981) …”

Utility of Slepian basis functions for modeling near-surface and satellite magnetic anomalies of the Australian lithosphere

“…Additional approaches to local spherical coordinate magnetic anomaly analyses have invoked inversions using equivalent point dipoles (e.g., von Frese 1998;von Frese et al , 1988Hinze et al 2013) and spherical cap harmonic functions (e.g., Haines 1985Haines , 1990Thébault et al 2006). Spherical cap harmonic functions in particular have been widely applied for modeling main field and secular variations (e.g., Haines 1985;Kotzé 2001;GayaPiqué et al 2006), and lower-order lithospheric components of the Earth's magnetic field (Coles 1985;de Santis et al 1989;Kovács et al 2011).…”

Crustal field recovery and secular variation from regional and global models over Albania

“…In order to recover the static crustal field from the observed data we devise a regional model available for small region of Earth's surface. Regional models are normally based on a denser data grid than global models and for this reason produce more accurate results over the same region than the global ones [Haines 1990]. One of our regional models consists on the expansion of the geomagnetic field components in Legendre's polynomials.…”